Suction mechanism



April 2, R. B. SA'RGVENT Re. 21,416

sue-non 112cm: s

Original Filed-Dec. 18, 1937 I ma a Apr. 2, 1940 UNITED STATES SUCTIONmechanism Richard B. sail-gent, Philadelphia, Pa., assignor to The HaleFire Pump 00., Inc., Conshohocken, Pa., a corporation of PennsylvaniaOriginal No. 2,180,259, dated Novemberdd, 1939,

Serial No. 180,654, December 18, 1937. Application tor reissue February8, 1940, Serial No.

3 Claims. (Cl. 230-95) This invention relates to improvements in suctionmechanism of the type utilizing for motivation the fluid pressuregenerated in the exhaust 01 an internal combustion engine. Such.mechanisms may be employed, forexample, for priming centrifugal pumps,and are of particular utilityin connection with fire flghting apparatuswherein the internal combustion motor of the flre engine is commonlyemployed to drive the pump or pumps forming essential elements of theequipment.

A principal object of the present inventionis to provide a device of thestated type that by reason of a novel design hereinafter described willexhibit in operation. a performance in the pump priming functionmaterially in advance of the prior commercially available devices ofthis character.

More specifically, an object of the invention is to provide a mechanismof the-stated type that shall be capable of producing relatively highdegrees of vacuum. a

The invention further resides in certain novel structural details andarrangements of parts hereinafter described and illustrated in the at-.-tached drawing, in which:

Figure l is a view in perspective of an ejector made in accordance withmy invention and constituting an element of the suction mechanism;

Fig. 2 is a longitudinal sectional view of the ejector;

Fig. 3 is a section on the line 3-3, Fig. 2.

Fig. 4 is a detached view in' perspective of one of the ejectorelements, and

Fig.v 5 is a line drawing showing the suction mechanism as a whole.

With reference to the drawing, the ejector in a preferred embodimentcomprises three principal elements consisting, respectively, of acylindrical housing I, a nozzle 2, and a body member I. The housing I isprovided at one end with a threaded port 4 for connection with theexhaust manifold or exhaust pipe oi an internal combustion engine, andis provided at itsopposite end with an outwardly projecting annularflange I having tapped holes for reception of screws 8 which secure thebody member 3 to the housing.

.- Intermediate its ends the housing has in its in- 1 er wall an annularrecess I, and a tapped port I i'ormedinabosst onthe wall oi'thehousing"communicates with said chamber. The housing further is'provided with aninternal flange II Kwliich provides a solid abutment or seat for thenozzle 2.

The nozzle 2 is formed at its rear and, namely,

neatly flt within the bore of the housing I, and

that end which in assembly abuts the flange II, with acylindricahsurface I2, and this surface, as shown in Fig. 4,'neatly fltsthe bore of the housing I. From this end the body of the nozzle 2 tapersinwardly to a cylindrical extension I3 of 5 relatively small externaldiameter. Ribs Iliextend outwardly at the base of the extension I3, andthe outer surfaces of these ribs flt neatly against the inner wallsurface of the housing I, as shown in Figs. 2 and 3. These ribs, withthe surface I2, form an extended bearing for the nozzle upon the housingand maintain the nozzle definitely in a concentric position within the.housing bore. The bore of the nozzle at the end adjoining the flange IIis conical in form, as indicated at I5, and the inner end of thisconical poi'tion terminates in a cylindrical passage I6 which extendsthrough the extension I3 of the nozzle.

' The body member 3 is formed at one end to is.provided intermediate itsends with an outwardly extending flange II through which the bolts 6pass. It will be noted that in assembly the'flange II does not engagethe flange 5 of the housing, so that when the bolts 5 are tightened, theinner end of the body member 3,-which engages the end edges of the ribsI4, forces the nozzle 2 solidly against the abutment flange II. Thethree principal elements of the nozzle are thereby held securely intheir relative positions in the assembly by means solely of the bolts 6,and by removing these bolts the nozzle structure may be disassembledwithout disturbing the connections at the ports 4 and 8 01' the housing.The body member 3 provides a rearwardly tapered passage l8 which at itsinner end communicates directly with the nozzle passage I6, and as shownin Fig. 2, the passage ll of the body member communicates at its rear orinner end with a conical terminal recess I9, which through the spacesbetween the ribs I4 of the nozzle 2 is in direct communication with theannular chamber I. By reason of the neatly fltted contacting surraces orthe body member 3 and the housing I, and the similar close fit betweenthe nozzle 2 and the housing, the bores of the nozzle 2 and or ,chamber1 and tends to draw into that chamber.

through the port 8, fluid from a source with which the said port isconnected. When this device is employed for priming centrifugal pumps,the port 8 is connected with the eye of thepump in well known manner.

of an ejector adapted to operate at the. relatively low gas pressuresavailable-in the exhaust of an internal combustion engine," and toproduce the required relatively high lifts, pre? sented a problem ofconsiderable complexity involving deflnitedeparture from theconventional design practice. It was n to consider not only thecharacteristicsof'the ejector per so at the available pressures, butalso the effect of the presence of the e'jector in theexhaust line uponthe operation of the engine which constitutes the source of theoperating pressure'when said engine is functioning as an exhaust gascompressor.

The velocity of the gases discharged through the ,ejector nozzle is afunction of the exhaust pressure, whereas the-pressure developedin theexhaust is a motion of engine operation, the eiii- I ciency of whichoperation, whensaid engine is functioning as an exhaust gas compressor,being determined by the diameter and form of thenomle e of the nozzle. Ihave discovered that if the diameter of'the nozzle is too great,

the exhaust pressure obtainable from the engine when said engine isfunctioning as an exhaust gas compressor, is not sufilcient toprovidemaximum suction at the ejector, due to the fact that the exhaust gasespass too freelythrough the nozzle without building up a sufiicient backpressure. I have discovered, on the-other hand, that ifthediameterofthenozzleistoosmall,theexhaust pressure or pressure will be too greatbetween the engine and the ejector to permit the efficient operation ofthe engine when said engine is acting as an exhaust gas compressor, dueto the fact that the excessive exhaust back pressure existing betweenthe en-y gine and the ejector will materially interfere with theoperation of the engine, 1. e., it will prevent the engine fromoperating smoothly and properly, and if too great will even cause theengine to stop. I have discovered that there is-a direct relationbetween the diameter and shape ofanozzleinsertedin-theexhaustofaninternal combustion engine and theexhaust pressure of that engine and that it is possible to design anomle which, within definable limits of size and shape, will beproductive of the development ofmaximum attainable exhaust pressures bythe engine when said engine is functioning as an exhaust gas compressorand, therefore, of maximum yelocities -of gas discharge through thenozzle. Velocity alone ispot s'uiiicient, on the other hand, to obtainhigh lift characteristics in'the ejector, these characteristics being afunction of the relation of the nozzle to the other elements of theejector and the form and relative dimen sions of those elements. I havediscovered that between definable limits there is a direct relationbetween the forms and relative dimensions of the nozzle and of the otherelements of the ejector affording maximum lift characteristics in theejector. I have found further that all of a these relations aresubstantially constant, and that they may, therefore, he expressed interms of formulae permitting y application of the principle involvedtothe reduction of ejectors for use with substantially any character ofinternalg combustion engine and capable of ail'ord-' ing, when used withany specific engine, performances heretofore considered unobtainable.

Referring again to the drawing, I have found that maximum velocity ofnozzle discharge may be obtained by the exhaust gases of an internalcombustion engine through a nozzle e of the cylindrical form shown wherethe diameter (DN) of the e, in inches, is approximately 35 of the squareroot of the maximum brake horsepower of the said engine, and' the lengthof the passage (LN) is approximately three times its diameter. Withanozzle passage of this with the ejector connected to the exhaust of aninternal comhustiorr engine when said,.engine is functioning as anexhaust gas compressor, the exhaust pressure may be developedtoestahlish the maximum suction at the ejector. This is accomplished by.running the internal combustion engine withthe throttle thereof at thewide open position, for it is at this pofltion of the throttle that theengine develops its maximum brake horsepower. with a nozzle passage of adiameter in inches of approximatelylfi ofthesquarerootofthemaxb' mumbrake horsepower of the internal combustion engine, maximum velocity andpressure ef-' fects will be obtained at the ejector and the said enginewill operate smoothly and efficiently as an exhaust gas compressor. i.e., no excessive back pressure will be built up between the elector andengine which would tend to affect adversely thenormal operation of theengine as an exhaust gas compressor and the. nozzle e is suchthattheexhaustgasdoesnotpasstooreadily therethl'ough. I have foundfurther that exceptionally good rsults may be obtained by variationofthese dimensions in either direction between certain limits. Thus thediameter of the nozzle emayvarybetweenyi andl of the square root of themaximum brake horsepower of the engine, and the length of the nozzle mayvary between 1% times thediameter of the nome e and five\ times said.diameter. These .-therefore, may be express in tergns 'of the followingformulae:

---braie iiliaxlimufmbrake 8 engine 15 30 VILN=DNX 1% to mvxs The limitsspecified in the above formulae have been foundto define a critical oroptimum range of dimensions, outside of which maximum suction effectsare not obtainable at the ejector. If the diameter of the nozzle passageexceeds the above specified maximum, theexhaust-e gases pass too readilythrough the nozzle, whereas if the diameter of the nonle passage, isless than the above specified minimum, the ,back pressure is too greatand affects adversely the efficient operation .of the internalcombustion engine. when I refer to the emcient operation of the engine,it will be understood that I refer only to the efficiency of the engineto function as an exhaust gas compressor, i. e., I am not at allconcerned throat diameter (DB) of the passage It. The

- with the efiiciency of the said engine to perform other work, such asdriving a pump, propelling the vehicle, or the like, it being obviousthat the ejector is connected to the engine only during such time as thesaid engine is functioning as a source of exhaust gas pressure for theejector.

As previously set forth, I have found further that to utilize thevelocities thus afforded to obtain a maximum lift in the ejector, theelements of the ejector structure should bear, between certain limits, adefinite relation to each other. Thus the passage ll through the bodymember 3 should diverge forwardly from a point of maximum restrictionadjoining the nozzle 2, and this angle of divergence (a) should beapproximately 2, and may vary between 1 and 3". The diameter of thethroat of the passage l8, 1. e., the diameter (DB) at the point ofmaximum restriction, should for best results be approximately 1.5 timesthe diameter (DN) of the nozzle passage, and may vary between 1.3 timesthat diameter and 1.7 times the diameter; and the outside diameter (dN)of the outer end of the nozzle 2 which lies in proximity to the throatof the passage l8 should be from 9;" to plus the diameter (DN) of'thenozzle passage. It was found that the length (LB) of the passage l8should for maximum results be approximately 7 times the diameter (DB) ofthe throat of the passage, and may vary between 4.5 times the diameterof said throat and 10 times the diameter of the throat.

The end of the nozzle 2 in this assembly is preferably located at thethroat of the passage II, but may occupy a position at either axial sideof this throat to a distance (A) up to .5 of the foregoing dimensionsmay be expressed in terms of the following formulae:

dN=DN+JW to DN+ a. DB=DN 1.3 to DNxL'l a =1 to 3 .LB=DB- 4.5 to DB 210A, the distance of the end of the nozzle 2, in either direction axially,

from the throat of the passage ll, may vary within the-limits of zero toDBx .5;

ejector.

It will thus be seen that the most important dimension or rangeofdimensions relates to the diameter DN of the nozzle passage, and thatonce this dimension is obtained by using the known maximum brakehorsepower of the engine as a basis for the calculations, the length ofthe nozzle passage LN, the diameter of the throat of the bore DB, et'c.,may be readily determined. Hence, by the invention presented herein itis a relatively simple matter to associate with any internal combustionengine of known maximum brake-horsepower, the proper ejector mechanismto accomplish optimum maximum suction effects. The maximum known brakehorsepower of a particular engine is generally set forth in thespecifications of the engine and hence is a known quantity. Such factorsas the area of the pistons in inches, the pressure in pounds weight persquare inch, the length of the stroke in inches, the number of strokesper minute, the number of cylinders, etc., al1 contribute to thedetermination of the maximum brake horsepower for any'given'maybeusedasabasisfo -metric displacement of the engine when consideringsaid engine as an exhaust gas compressor.

I have discovered that the maximum brake horsepower of an internalcombustion engine calculating the dimensions of the componen parts of anejector, which ejector, when connected to the exhaust of the selectedinternal combustion engine and said engine operated at wide open"throttle, will develop maximum suction eflects at the ejector.

with an ejector constructed as described above, I have found it possiblewith the pressures avail able from the exhaust of an internal combustionengine, which' pressures are seldom in excess of 25 pounds, to liftwater vertically through heights as great as 24 feet; this lift beingfar in excess of the lift previously obtainable by ejector action fromsuch exhaust pressure source. While it is known that prior to myinvention attempts have been made to utilize ejectors operated from theexhaust of an internal combustion engine for the purpose of primingpumps, such attempts within my knowledge have failed in commercialapplication by reason of inability to produce by this means lifts ofadequate height. 'The present invention finds an application ofparticular value in connection with centrifugal pumps employed in firefighting apparatus wherein the priming operation may frequently involvelifts of watei from the source to the pump of considerable heights. Itis customary in modern fire fighting apparatus to provide the vehiclewith an internal combustion engine which is selectively employed topropel the vehicle, or to operate the pumping equipment on the vehiclesuch as a centrifugal pump or the like. It is therefore a matter ofgreat convenience to utilize the internal combustion engine mounted onthe vehicle as a source of pressure fluid for operating an ejectoradapted to create maximum suction effects for pump priming and/or otherpurposes.

I claim:

1. A suction mechanism comprising an ejector connected to the exhaust ofan internal combustion engine of known maximum brake horsepower, whichengine functions as a source of pressure fluid for operating theejector, said ejector including a nozzle having a cylindrical passagethrough which the exhaust passes, a body member having a bore arrangedin axial alignment with the nozzle passage and extending forwardly fromthe latter, said bore diverging towards its forward end and said nozzlebeing arranged with its forward end in proximity to the throat of saidbore, and means providing a suction chamber outwardly of said nozzle andcommunicating with the rear end of said bore, said nozzle structureconforming to the terms of the following formulae:

Maximum brake H. P. of engine Maximum brake H. P. of engine LB=4.5DB toIODB DN- to where DN is the dimeterin inches of the nozzle passage, L Nis the '{length of the nozzle passage, DB is the diameter of the throatof said bore, 0 is the angle of divergence of said bore, A is thedistance oi the forward end oi said nozzle from said throat in eitherdirection axially oi the bore,LBisthelensthotsaid bore,anddNis theoutside diameter of the nozzle at the forward end thereof which lies. inproximity to the throat 01 said bore.

2. A suction mechanism comprising an ejector connected tothe exhaust ofan internal combustion engine oi known maximum brake horsepower, whichengine functions as a source 01 pressure fluid for operating theejector, said ejector includink a first nomle having-apassage throughwhich the exhaust a second nozzle having a bore axialLv aligned with andextending-forwardly from the forward end oi the first. nozzle, and achamber outwardly of. said first nomle'and communicating with the rearend of said bore, said first nozzle e being cylindrical in term andhaving an internal diameterininchesequaltofi'om A toys oithe square rootat the maximum brake horsepower oi the ensine with which said ejector isto be connected whereby emcient operation 01' saidensine for productionof pressure fluid for suetion effects may be obtained.

3. A suction mechanism as defined in claim 2, wherein the first nozzlediameter of said nozzle mcnarm B. sananu'r.

e has an efiectivefi length equal to from 1% to timesthe internal

